<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <script src="../vue.js"></script>
</head>

<body>
  <div id="app">
    <h2>{{counter}}</h2>
    <!-- <button v-on:click="counter++">+</button>
    <button v-on:click="counter--">-</button> -->
    <!-- <button v-on:click="increment">+</button>
    <button v-on:click="decrement">-</button> -->
    <!-- 语法糖 @写法 -->
    <button @click="increment">+</button>
    <button @click="decrement">-</button>
  </div>
  <script>
    const app = new Vue({
      el: "#app",
      data: {
        counter: 0
      },
      methods: {
        increment() {
          this.counter++
        },
        decrement() {
          this.counter--
        }
      }
    })
  </script>
</body>

</html>